Faint Ring Thread, Saturn's D, E and G rings Options

[Rob Pinnegar]

There are two new "Raw Images" up that give a good view of Saturn's D Ring. As of today (July 17th) they are on the first page of the Raw Images section. The better of the two is image number W00009347.

The very narrow inner ringlet is called D68 and it is the innermost well defined ringlet of the entire ring system -- it's only about 7250 kilometres above the cloud tops, about half-way from the planet to the inner edge of the C Ring. If you search the "Saturn-D Ring" section of Raw Images, there is a nice narrow angle view (N00035241) which I am pretty sure is a close-up of D68. D68 is an oddball, it really is sort of "in the middle of nowhere".

The brighter ringlet in the upper right is called D73. About a thousand kilometres inward from D73, there is a noticeable "dark zone". In the Voyager images, there was a third bright narrow ringlet inside this zone, D72, which seems to be gone now, strangely enough. The relevant Voyager images are Voyager 1 image 34946.50, and Voyager 2 image 44007.53. If the diffuse ringlet at the inner edge of the "dark zone" is what is left of D72, it looks to have migrated a bit closer to Saturn in addition to spreading out a lot. (By the way, I'm not making up these ringlet designations on the fly -- they are given in a paper by Mark Showalter that was published in Icarus in 1996, which is pretty much the only major paper on the D Ring.)

To give some idea of scale, the three bands of material in the far upper right corner are part of the innermost ringlet of the C Ring (this can also be seen on some images of the rings taken on May 3rd of this year).

Since it is so faint and doesn't appear in many images, the D Ring rarely attracts much attention. But it's kind of neat to look at if you haven't seen it before, particularly because of D68, which is sort of the "anti-F ring" in a way.

[geckzilla]

A quick, probably simple question... I wondered if this is a more or less correct guess: Are the E and G rings are kind of reflective or glossy like snowflakes? I see the way they are illuminated in the famous Saturn ring portraits and the bright points line up with the sun in the same way a glossy reflection would. The rings are of course made of many particles so the effect is diffuse and smooth. I circled what I am describing in the picture to ensure there is no confusion about what I am asking.

As a way to teach myself how to use Blender effectively I have been trying to copy various physical effects. I found that a good way to simulate the outer rings was with a hacked glossy material (I can't make a glossy volume...). My fake Saturn is here if you are curious. (If Björn Jónsson happens to read this, you are awesome and I thank you for providing all those image maps.)

[john_s]

"Glossy" is the wrong word- that implies a specular (mirror-like) reflection. What's going on in this image instead is that there are small particles in the G and E rings which become particularly bright when the sun is almost directly behind them (in the same way that smoke is most conspicuous when backlit by the sun). The parts of those rings that are closest to being exactly backlit are the brightest, and those parts are close to Saturn, because the Sun is behind Saturn.

John